Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/40—Chemically transforming developed images
  • G03C5/44—Bleaching; Bleach-fixing

Definitions

• This invention relates to photographic bleach compositions and to methods of photographic processing employing such compositions.
• Bleach baths are widely used in photographic colour processing to remove image silver so that only dye image remains. In many instances it is convenient to use a combined bleach and fix bath and this is known as a bleach-fix bath.
• ferricyanides are not used in commercial bleach-fix baths; they tend to employ ferric ions complexed with either ethylene diaminetetracetic acid (EDTA) or nitrilotriacetic acid (NTA) even though many other complexing agents have been proposed.
• EDTA ethylene diaminetetracetic acid
• NTA nitrilotriacetic acid
• Ferric EDTA and NTA are not always suitable for bleach baths as they are slower than ferricyanide bleaches and not sufficiently strong to oxidize some image dyes leaving them in their less strongly coloured leuco form.
• Bleach-fix baths are also widely used in photographic colpur processing and, as their name suggests, combine the functions of a bleach and a fix bath.
• German Patent Specification 866,605 (published in 1953) describes bleach-fix baths in which the bleaching agent is a ferric complex of an organic acid of the general formula: HOOC-R 1 -X-R 2 -COOH or HOOC-R 4 -N-R 3 -COOH
• R 1 , R 2 and R 3 represent hydrocarbon radicals which may be substituted and R 3 may also represent hydrogen, and in which R 4 , R 5 and R 6 represent bivalent hydrocarbon radicals which may again be substituted.
• R 4 , R 5 and R 6 represent bivalent hydrocarbon radicals which may again be substituted.
• EDTA EDTA
• NTA ethyliminodipropionic acid
• EIDPA ethyliminodipropionic acid
• the present invention provides photographic bleach compositions which are more active than ferric EDTA, NTA or IDA compositions and which are free from the environmental and commercial objections to the photographic bleaching agents mentioned above.
• a photographic bleach composition which comprises bleaching agent a ferric complex of an alkyliminodiacetic acid the alkyl group of which may be substituted.
• the present invention further provides a method of processing a photographic colour material which comprises the steps of bleaching the material containing both a silver image and a dye image with a bleach composition according to the present invention and either simultaneously or subsequently fixing the material.
• Any photographic silver halide emulsions may be used in the materials to be processed with the present bleach compositions. These emulsions may comprise silver chloride, silver bromide, silver bromoiodide, silver chlorobromide or mixtures thereof. Coarse grain or fine grain emulsions prepared by any of the well-known procedures may be used. The emulsions may contain any of the known chemical sensitizers, colour couplers, spectral sensitizers, antifoggants, stabilizers, coating aids and other addenda used in photographic materials.
• the silver halide emulsions may contain a hydrophilic colloid, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextrose or gum arabic, or synthetic polymeric substances, for example, the water-soluble polyvinyl compounds, poly(vinylpyrrolidone) and acrylamide polymers.
• a hydrophilic colloid for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextrose or gum arabic, or synthetic polymeric substances, for example, the water-soluble polyvinyl compounds, poly(vinylpyrrolidone) and acrylamide polymers.
• alkyliminodiacetic acids which may be employed herein preferably have an alkyl group having 1-6 carbon atoms.
• the substituent on the alkyl group may be, for example, a hydroxy group.
• Examples of particular alkyl and substituted alkyl groups which may be present on the alkyliminodiacetic acid are methyl, ethyl, n-propyl, n-butyl, n-amyl, hydroxyethyl and hydroxy-n-hexyl.
• the ratio of alkyliminodiacetic acid to ferric ions in the present compositions may vary widely, for example from 1:1 to 15:1, optimally from 1:1 to 5:1 on a molar basis.
• the present bleach compositions may also contain other bleaching agents, for example, ferric EDTA, or any of those listed in British Specification No. 1,340,131 or U.S. Patent No. 3,694,462, in addition to the bleaching agents specified above.
• the working strength bleach solutions may have a pH in the range 5 to 7 preferably pH 6.0 and will preferably contain a water-soluble halide, e.g., for colour films, potassium bromide in a concentration of more than 40 g/litre, preferably from more than 60 g/litre up to the limit of solubility.
• the present bleach solutions are more effective than ferric EDTA bleach solutions due to the higher oxidation potential of the ferric alkyliminodiacetic acid complex. Consequently either faster bleaching can be obtained from an equivalent solution or equivalent bleaching can be obtained from a solution containing less halide or bleaching agent.
• the present compositions may be stored in very concentrated solution, e.g. containing from up to 540 g/litre of bleaching agent, enabling kits of processing chemicals to be compact.
• the present bleach solutions may contain a silver halide solyent, preferably an ammonium or alkali metal thiosulphate, in which case they become bleach-fix solutions.
• Example 1 A series of bleach solutions was prepared according to the following formulations: 0.02M ferric chloride 0.1M potassium bromide 0.25M alkyliminodiacetic acid The alkyl of the alkyliminodiacetic acid was methyl (MIDA), ethyl (EIDA), n-propyl (PIDA) or n-butyl (BIDA). These solutions were adjusted to pH 6.0 with ammonia and were used to bleach strips of exposed and developed medium speed black and white film, for varying times.
• MIDA methyl
• EIDA ethyl
• PIDA n-propyl
• BIDA n-butyl
• Example 1 The photographic testing procedure of Example 1 was repeated except that the bleach and fix solutions were replaced by a single bleach-fix solution of the formula: 0.25M ferric chloride 0.25M acid

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

Priority Applications (1)

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Publications (1)

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Cited By (8)

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Citations (7)

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• 1979
  • 1979-09-12 IT IT7925699A patent/IT7925699A0/it unknown
  • 1979-09-14 BE BE0/197165A patent/BE878806A/fr not_active IP Right Cessation
  • 1979-09-14 DE DE7979901091T patent/DE2964021D1/de not_active Expired
  • 1979-09-14 JP JP50144779A patent/JPS55500704A/ja active Pending
  • 1979-09-14 WO PCT/GB1979/000152 patent/WO1980000624A1/en not_active Ceased
• 1980
  • 1980-04-08 EP EP79901091A patent/EP0020397B1/en not_active Expired
  • 1980-05-14 US US06/192,952 patent/US4294914A/en not_active Expired - Lifetime

Patent Citations (7)

Non-Patent Citations (1)

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